It is well known in the art that flaring of low pressure hydrocarbon gases having a molecular weight ratio of hydrogen to carbon less than 0.30 tends to produce smoke as a result of incomplete combustion and the formation of free carbon. The release of free carbon to the atmosphere creates a dark smoke plume which is unsightly and a matter of poor ecological practice. Of the various means devised for coping with said smoke generation, two methods have gained primary attention. The first method involves the introduction of a smoke suppressant, typically steam or water, to the combustion zone. The water, in vapor phase, reacts with the hydrocarbon by familiar and well-known endothermal reactions. The second method relates to the use of air-powered flares which provide turbulent mixing of air with the hydrocarbon gas for complete smokeless combustion.
The flaring of high pressure hydrocarbon gases is different, however, and does not require additional energy as the relatively high pressure of the gas, upon release, provides sufficient kinetic energy for the system to operate smokelessly. Since the flaring of low pressure gas requires additional energy to be imparted to the system, and, whereas the flaring of high pressure gas does not require additional energy, separate flare systems are normally used for the different pressure waste gases, because lower pressure gas obviously cannot be vented to relief lines carrying gas at a higher pressure. This results in high capital and maintenance costs, the disadvantages of which are apparent.